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A. G. CHAPMAN WAVE ANTENNA ARRAY Feb. 3, 1931.

Filed Aug. 23, 1928 2 Sheets-Sheet l F 5d NZLTOR B6'. CWI/@alfa ATTORNEY Feb. 3,11931. A'. G. CHAPMAN 790f742 wAvE ANTENNA ARRAY I Filed Aug. 2s, 1928 2 sneetsfsneet 2 Pair 4 Pair . INVENTOR G'. WwW/y I I BY fw:

ATTORNEY Patented Feb. 3, 1931 UNETED s'm'ras PATNT'JQFFIJCE ARTHUR. G. CHAPMAN, or' UPPER MoNTcLAIR, NEWJE-nsninssrenon 'ro MnnioAN TELEPHONE Ann Tannen-PH lceirenn, r; oonro'nn'rron ,oF NEWYORK WAVE-ANTENNA ARRAY f1 Application filed August 23', 1928. Serial 110,301,612,

. r This invention relates to radio receiving systems and particularly to an antenna sysf Twhich Figur-e1 shows schematically a form tem employing a plurality -of wave antennae staggered longitudinally, the said antenn l 5 being so arranged and connected that the currents set up in certain of said antennae by waves from an undesired direction may be opposed to the current set up by the same waves in another of -said antennae and thus i() :neutralized lVave antennae are well known in the art, Y

having been disclosed in the patents to Bever- 1' Aage and others, and in technical publications.

Y `A radio receiving system, consisting of twoparallel like wave antennae separated by a' fraction of awave length and with one an- IV tenna displaced longitudinally a fraction of j a wave length with respect to the other, has been called a staggered system. v The antennae must be separated 1,000 to 1,200 feet apart to minimize crosstalk-between them and `each antenna requires a pole line for its support u and a transmission line to bring the received L currents to the radio receiver.` Furthermore, the separation of the antennae produces a broadside eHect, that is the effect of space 1 phase change from one antenna to the other in undesired waves received from points not in line `with the antennae in either direction,

'B0 which-effect must be taken into consideration.

In my copending application Serial No.

235,303, filed November 28, 1927, is described' r sired waves in two of said antennae may opvpose and neutralize the current from the same undesired waves in the third antenna thereby givingto the entire antenna system a .sharpv receiving characteristic.

This invention Vwill be clearly understood and connected that the currents from'unde' from the following description when read in connection with the attached drawing of of the embodiment of the invention; Fig. 2 which in general is similarI to Fig. 1 shows 4in greater detail the mode of connecting the antennae; Figs. 3a, 3b, V30 and 3d arecurves lantennae which are' parallel and staggered a predetermined distance.f-Thus the antenna 2 is staggered a distance of '2d Awitlrrespect to antenna land antenna Sis staggereda dis- 'uators to have effectively the same `length as indicated schematically in Fig. 1. I Theends of antennae 1v and 2 are connected by transmission" lines 4 and 6 with a network` HC1 which network serves to combine the currents from the antennae l and 2.' While various types of combining networks may beA remployed, a preferred lform` is that disclosed in Fig. 2 of the drawing filed with the applica-- tion -of Bailey fand Dean', Serial No. 183,532, filed April 13,1927; '/Thetransmission line 6 contains an artificial line N1 for retarding the Vphase of the current being transmitted from `the antenna 2 to the network HC1 prior to impressing thevsaid current upon the network. v The output of HC1-is connected withV the combining network HG2, the connection .including an `atten'uator A, to Asuitably reduce theourrent transmitted from` the net* work HC1 to the network HG2 and a transposition to 'reverse the phase of the current entering H021 The` antenna, 3 is alsoA connected .with theV network HG2 through an artificiallineN2 which retards the phase 'of 'the current transmitted Afrom antenna 3 'to network HG2.` #The Output of the vnetwork and vvector diagrams illustrating theprin- 7o a In practice, the

HG2 may be connected with any form of` receiving apparatus indicated by R.

It will be apparentthat the currents set Vup in the antennae of the array by any source locate the antenna array` that itsl longitudinal i axis points toward the station from which it is desired to receive signals. YThe antenna system and associated artificial lines and attenuators are then arranged so as to produce zero reception from certain directions and a minimum from directions other than thzltt from which it is desired to receive signa s.

Let it be assumed that itis desired to receive zero current from a direction at an angle 9 equal to 180 degrees removed from the direction of the desired signal'. The staggering distance d and the phase change in artificial line N1 are so chosen'that when 9 equals 180 degrees, the currents and y are in phase. Those vcurrents Awill be added andthe resulta-nt will, of course, lbe twice that of eachl separateo antenna. Since that current is to be used to neutralize the current set up by the same wave in antenna 3, itV

must be reduced one-half in network HC1 and attenuator'A1 in order to effect neutralization. The resultant current, namely y-l-x,

is then reversed inrphase by a transposition and impressed upon the network HCZYtogether with the current a which is transmitted from the .antenna Y3 over the transmission line 5 and changed in phase by artificial line N2 to bring it in phase withg/ and '.r. By opposing those currents in the net-v work HG2, neutralization is obtained of current resulting from waves striking the antenna system from a direction 180 degrees from the desired'direction. Fory this direction, the currents entering HG2 are in opposite phase at all frequencies if 'the phase changes of artificial lines Nl'and N2` increase directly as the frequency. The array `characteristic, i. e., the ratio of theY magnitude of gcurrent/w to that of current a, is shown in Fig. .3a.

i 'shows' the array characteristic for VcZ:1/8

For

wave length and a null point at160".

VZ:1; wave length for the frequency 'of the desired signal and a null point at 180 degrees the vector diagrams of Figs. 3b, 3c and 3d show the phase relations of current a, and y and also the phase relations of The diagrams are given for 0:0,"90 and 180 where 0 is the angle between the direction of an undesired signal and that of the desired signal. I

Fig. 2 shows how .the individual antennae of Fig. 1 would be terminated and coupled with transmission lines in order to contain the desired combination of currents.

The diagrams of the group of figures assume no lateral spacing between the three antennae. If a system were actually constructed in accordance with Figs. 1 and 2, it would be necessary to use appreciable lateral spacing between lthe antennae to avoid cresstalk between them unless the antenna length were equalto or'less than d. This lateral spacing improves the array .factor from 0:0 to 0:1550o and'degrades it from 0:1530o to 0:3600. yThe eHect may be reversed by interchanging antennae l and 2. For example, fora 'lateral spacing between adjacent antennae of gth wave length, the array characteristic is changed from .29 to .077 at 0:90o and from .29 to .62 at 0:270. For angles near Zero. or 180 the array factor is little dependent on the lateral spacing. If the undesired; signals come mostly from one side of the array, the distortion of the array factor, due to lateral spacing, is not objectionable. To avoid this distortion, and avoid the use of three separate pole lines a special antenna shown in Fig. l may be used instead of the simple antennae l, 2 or 3 of Figs. 1 and 2. Such an antenna would have about the same directional characteristics as the simple. antenna and about one half the strength of desired signal. The yspecial antenna consists of a series of short a-ntenn each of lengthd and spaced longitudinally at distances d; The short antennae are connected to a combining network H03 through like transmission lines and through artificial lines N3 to N6 to change the phases of the individual currents. The phase'changes of theseflines are adjusted to bring'the four currents entering HC3 into phase for the value of 0 at which is desired to have a null point. 'If three such special antennae are arranged as in Fig. 1, it will be seen that the 'last three sections of the upper antenna and the first three sections of the lower. antenna are unnecessary since the currents from these sections are mutually cancellingk in network HC1 for all valuesof 0. The array of three antennae may therefore be replaced by the arrangement of Figq. The short antennae of Fig. 5 may all be placed ona single pole L1.

" t With :ground-returmfthefmetallic pairs, may

p 'be used frthe transmission lines, vTas 'indithe transmission'l lines Lwould beJ-fcompen sated Vhyterminal articial lines andattenu ators to have the same total--phase-change and'attenuationi By using six pairs-,the sig-V `mnals from the individualshort-antennae may be transmitted t'oft-heend-cf thefline-nearest thel station-'fsending-athef-desired 'signal'; "rThis hasl the Iadvant'age thatsmuchr'smaller -values A of phas'e change needl toV be `suppli`ed :function in-thef same'man'ner 15 by the-flocal*artificial 'linesff Thelfmetallic pairsmust, oflfcours'e, 'be' carefully;ftgrans-A posed to avoidfscrosstalk between-them.

' vThe Aarrangement /shown inllli-g.Y 6 provfis which. isl the A"-1rightlhandterminall .l fsection will be connected directly with the terminal apparatus. j;'F.rom' 1- the foregoing -description' litfWill vbei-apparent that thefarrangement #shown inV Fi'gw provides a sectionalizedfantenna-y system that is capable not only intercepting-they electromagnetic: Waves but is-*also fcapable ottransmitting to the terminalapparatus ltheA lcurrents Llvresulting fromf-such interceptionl Thearran-gement shown'in Fig. i6" when thel sizrl pairs fof :termi- 1 .nals' atVv the IrightV are.A connected `to the six "artiii'cialllines N3 to N'6\,-shown in' Figv, Will the arrangei'mentg shoWnIi-nfFig. 1'.

-It'fis to beiunderstodd" that'wh'ilelthe invention yhas lbeen-disclosed fin-certain -i'orms,

it -is-capab1e f of embodiment Aother forms Vides a system- 'ofconductors' that are'Capa- Withoutfdepartingfronrthe?spiritfand/scope t ble ofintercepting-the radio Waves jand oit' lof thev appended claims.- f

transmitting tol thefterniinal-=apparatus the --currents cre'atedwth'erebyvSuclv terminal u apparatusY-would -be= similar 'to'a that showin in Figs. 5 and l. Y'The arrangement in Fig What is ,claimed is:

`1. n-"affzradio signaling system', the com- "b'inatio'n with a-plurality eti-parallel an- 1 tennae, each vstagggered-llongitudinallyafracv5g-comprises v-ive "pairs ctv-Wiresthat ma'y'ltionA cfa wave-lengthwith respect'to the he supported uponfthefcros'sarms on `a' single Npoleline. Eachrpair of Wiresisisectionallized incr/manner corresponding to the six short antennae and three intervening spaces of Fig. 5. All of the Wires in each section corresponding to a short antenna of F ig.-5 are grounded at one end through a resist:

ance representing the characteristic impede ance of the five transposed pairs with ground return and at the other end through the Winding of a transformer, the other Windd ing of which is connected across one of the pairs of Wires of the succeeding section.' Thus, for example, all of the conductors of 40 the section AB are connected at the right'- others;A a receiving-circuit ldifrectly connected l'fu/ith one 'of {saidjantennae'fand by` 1nea-ns of transmissioni lines? With-' the {other} antennae, Ameans connected -loeinrveen said lreceiving circu'it-f andi "said "direct-connected* fantenna'vto 'elqiialize the magnitudes and''shift the Lrelaand-*another 'offsaid antennae; means toicomy bine 1 thel currents f ifroinmi-,hsaid direct-con 4netted'1antenna l-and the? sa-id:y other-antenna and fto'ffre'ducer the@-iesultantffeurrent Iby one half, anothervmeans `te'cmbine the' resultant currentlwith thevcurrent frointlief-third anl tennaand AmeansIfinterposedf betweenf said otherlcombining lmeans and-the transmission hand side with a Winding 0f a traDSfOrlTlTf-line 'of .1 said xthirdlf'antennatoeeqnale the imagnitudesfandishiit?the'rclativ'e phases of .v

the other Winding of which is connected across the conductors of pair l in the section- BC. It will be seen that by means of trans current set up in all the Wires of section AB and transmitted into pair l in the section f the currents `from'- f-i-tand-from theother antenn. Y i' formers at the section junction points, thef sections of that pair to the output of the final transformer at the right-hand side and from there to the left-hand artificial line N2, of Fig. 5. In like manner, all of the conductors of the section BC are connected t ground at both ends, the right-hand conf nection ,including a Winding of a transl former, the other Winding of Which is con"- nected across pair 2 in the section CD2V Current set up in all the Wires of section BC Will be transmitted along pair 2 to the right to the terminal apparatus at that end.'l In like manner the current set up in all'f the conductors of the sections DE, FG, and HI will be transmitted to the right over Wires 3, 4 and 5, respectively. Current set up in all of the conductors of section IJ'l Icotjerminolus at the section Y. jl'lnction'j points, means toconne ct all of,the',/conductors of ys.asection ,to. ground ationefen'd,` through a :resistance:representing thecharacteristic iml pedance of; the. section, rmeans to connect to ground all -so-ffthe conductors o-thesarne ssectior-r;through:the Winding of aa-trans- "gforme'rgf thel yothenwinding f of:i which is conf nected acrossa pair fof Vconductors 'of the aduja'cent: section .in theI direction ot VVthe termin'al1apparatus,A networkssconnected with cer- -{tain of s'aidl-pairslt'o equalizeiattenuation and shift phase, means tocombinecthecurrents ff-#romwcertainantennland to control .the f magnitude' 'of theuresultant fgcurrentg`f and "fmeansitQ/combiethe said resultantrscarrent 1 in thatsection by a wave may be impressed upon a pair of conductors of succeeding sec- 1 tionsfor transmission to aterminal circuit,

and means associated with said terminal cir-r cuit to combine the currentsfrom certain of saidantennae'in desiredphase and magnitude relations and to control the magnitude of the resultant current, and means to combine the resultant current with the current setup by the said wave in certain others vof vthe said antennae.

4. In a directive radio signaling system including an antenna array comprising more than two antennae, equally spaced apart and phase of the current in one of said antennae staggered longitudinally by a predetermined 1 distance with respect tothe adjacent antennae, :the method of eliminating undesired currents which consists 1n changing the so that itwill be in phase with the ycurrent in another of said antennae, :combining the v currents from the said one and said other Vof said antennae7 attenuating to a desired extent the current resulting from such combination, shifting byl80fdegrees the phase of the attenuated current,and then combining the said attenuated current with the current set up in a' thirdantenna of said directive signaling system. A

5. In a directive radio signaling system including an antenna array comprising more than two antenn, equally spaced apart andy staggered longitudinally by a predetermined distance withrespect to the adjacent antennae, the method of eliminating interfer-` lence from a predetermined direction -which consists in changing the phase of the current set up in one of said antennae by the interference from the Vpredetermined direction sothat that 'currentwill vbe in Vphase with the current set up by the same interi ference in another of said antennae, combin j ing the currents from Vthe said one and the said other antenn', attenuating to a` desired degree the resulting current from said comi binatio'n, shifting by 180 degrees the phase of the resulting current and combining the 'latter current with* the .current "set Vup by said interference in the third antenna of said array whereby the effect of the inter- 1 ference ,from a knowngdirection'is substan-V VAtially eliminated.

6; In a directive radiosignaling 'system including anf antenna array1 comprising more thanv two antennae, equally spaced apart and staggered longitudinally by a pre- 1 determined distance with respect to the ad- Y, 1

jacent antennae, the method of eliminating interference from a predetermined direction which consists in changing'the phase ofthe current set up in one of saidv antennae bythe interference from' the predetermined direction so that that current will be in phase with the current set up by the same interference in another of said antennae, combining the currents from the said one andthe said other antennae, attenuating to a desired degree the resulting. current from said com- ,binatiomshiftingby ISOVdegrees the phase of the Vresulting current, combining the latter current withthe current ls et up by said interference in the third antenna.4 of said array, and shifting to a desired Adegree the current set up in said third antenna by said interference, so thatthat current and the said resulting lcurrent vsubstantially neutral-l ize, and eliminatejthe effectuponrthe received signal of interference fromv a predetermined direction. l i

In testimony whereof, I have signed my name to 4this specification thisl2lst day of August, 1928. J ir ARTHURV G. CHAPMAN.

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